How to Execute old sql scripts only if there is any change?

Question

For eg.

If a table has 10 lakh records. If i run the script it will update the 10 lakh records.

Now, if i run the same script again it should not be executed because it was already executed before and also the table should not update since there is no change in the script .

Now, if the script is changed it should execute now....please help